Idle stop apparatus

ABSTRACT

An idle stop mechanism for a foot pedal ( 12 ) that comprises a column ( 32 ) that resists the motion of a foot pedal arm, the column being held so as to resist rotational and axial movement.

This invention relates to the field of idle stop apparatus for footpedals and in particular to such apparatus that have application in‘drive-by-wire’ applications for motor vehicles.

‘Drive-by-wire’ control systems for motor vehicles replace themechanical linkages between a control, for example a steering wheel or afoot pedal, and the vehicle system with which they are associated, forexample the steering rack or the throttle. Instead, an electrical signalis generated within the control and transmitted to an engine managementsystem which will then send one or more control signals out to variousvehicle subsystems, for example, to activate the brakes or to vary theamount of fuel being injected into the engine.

One of the requirements of ‘drive-by-wire’ systems is to have anaccurate determination of the idle point of the accelerator pedal, thatis the point at which no force is applied to the accelerator pedal bythe driver and thus the engine should only be operating at the idlespeed, which will be determined by the engine management system inresponse to the temperature of the engine, the electrical load which theengine must meet, etc. An accurate determination of idle point isimportant for the economic functioning of the engine and in order toreduce harmful emissions from the engine. Additionally, it is vital thatsmall changes in the control signal generated from the accelerator pedalcan be ascribed to a small movement of the pedal rather than hysteresisin the pedal mechanism, to give the driver control of the vehicle whenoperating at low powers, for example when parking and manoeuvring. Itwill be understood clearly that the present apparatus could also findapplication in conventional vehicles that do not use ‘drive-by-wire’systems.

According to a first aspect of the invention there is provided a pedalmechanism comprising a pedal mounted on a first end of a pivoted pedalarm, the second free end of the pedal arm being received within ahousing, resistive means urging the pedal arm in one rotationaldirection and opposition means that engage with the second end of thepedal arm and oppose the urging of the resistive means, the oppositionmeans comprising one or more axial engagement means that engage with thehousing to resist axial movement of the opposition means and one or morerotational engagement means that engage with the housing to resistrotational movement of the opposition means. Preferably, the oppositionmeans comprises a projecting member that is parallel and eccentric withregard to the axis of the opposition means, the projecting member beingreceived within the housing.

The rotational engagement means may comprise one or more teeth thatengage with corresponding teeth formed in the housing. This provides theadvantage that once the opposition means has been inserted into thepedal mechanism, the teeth intermesh and resist the rotation of theopposition means. The rotational engagement means may comprise anelongate member inserted through an aperture within the oppositionmeans. The axial engagement means may comprise one or more resilientmembers that grip the internal surface of the housing to resist theextraction of the opposition means once it has been inserted into thepedal mechanism.

According to a second aspect of the present invention there is providedan apparatus for opposing the motion of a foot pedal comprising acolumn, one or more axial engagement means and one or more rotationalengagement means, the column, in use, opposing the rotational motion ofa foot pedal. Preferably, the column comprises a projecting member thatis parallel and eccentric with regard to the axis of the column, theprojecting member being configured to engage, in use, with an aperture.

The rotational engagement means may comprise one or more teethconfigured to engage, in use, with corresponding teeth and/or therotational engagement means may comprise an elongate member configuredto engage with an aperture within the apparatus. These arrangementsprovide resistance to the rotation of the opposition means once it hasbeen inserted within a suitable housing. The axial engagement means maycomprise one or more resilient members configured to engage, in use, asurface to resist the extraction of the opposition means once it hasbeen inserted within a suitable housing.

The invention will now be described, by way of example only, withreference to the following Figure in which:

FIG. 1 shows a schematic depiction of a side view of a pedal mechanismincorporating an idle stop unit according to the present invention;

FIG. 2 shows a schematic depiction of a sectional view of a pedalmechanism incorporating an idle stop unit according to the presentinvention; and

FIG. 3 shows a schematic depiction of an idle stop unit according to thepresent invention.

FIGS. 1 and 2 show a side view and a sectional view, respectively, of apedal mechanism incorporating the present invention. Pedal mechanism 10comprises pedal 12, pedal arm 14, housing 16, sensor unit 18, idle stopunit 30 and friction unit 40. Pedal 12 is mounted on a free end of pedalarm 14 and when pressure is applied to the pedal from the driver's footthe pedal arm 14 rotates about a pivot 22. The pedal arm is coupled to asensor unit 18 that produces an output that varies with the degree ofrotation of the pedal arm; this output is preferably an electricalvoltage that can be transmitted to the engine control unit which willregulate the behaviour of the vehicle systems in response to therotation of the pedal arm and hence the position of the pedal. The pivotand the pedal arm are received inside a housing 16 that comprises a base20 for fastening to the interior of a vehicle.

Friction unit 40 provides a ‘feel’ to the pedal mechanism that issimilar to the ‘feel’ of a traditional accelerator pedal. Frictionelement 40 comprises piston 42 which is received inside cylinder 44. Thefriction element additionally comprises a resistive element that urges arounded end of piston 42 into contact with the interior wall of thehousing 16 that is opposite to the base 20. As the pedal is depressedand the pedal arm rotates, the rounded end of the piston moves acrossfriction pad 24, which is embedded within the housing 16. Frictionelement additionally comprises a resistive element (not shown) thatopposes the rotation of the pedal arm as the pedal is depressed. When nopressure is applied to the pedal the resistive element urges the pedalarm back to its rest position.

Idle stop unit 30 is shown in greater detail in FIG. 3. FIG. 3 a showsone side view of the idle stop unit, FIG. 3 b shows a side view that isperpendicular to the view shown in FIG. 3 a and FIG. 3 c shows a planview of the idle stop unit. The idle stop unit 30 comprises eccentricstop 311, column 32, surround 33 a plurality of engagement means 35,gear wheel 34 which comprises a plurality of teeth 37 and aperture 38.Eccentric stop 31 is received in a hole in the side of the casing 16such that the free end 15 of the pedal arm 15 that is contained withinthe housing rests upon column 32. As the free end 15 is urged towardsthe column by the resistive element of the friction element 40 it isimportant that the column is located within the limits of travel of thepedal arm.

Gear wheel 34 is provided to mesh with a corresponding set of teeth thatis arranged around a second hole that is located on the face of thehousing opposed to the first hole that receives the eccentric stop 31.The idle stop unit is partially inserted through the second, toothedhole until the stop 31 is received within the first hole. Once thecolumn is in the correct position with respect to free end 15 of thepedal arm the idle stop unit can be fully inserted into the housing. Theend of column section 32 butts up against the inside of the housing 16as it is unable to pass through the first hole and the resilientengagement means 35 will snap onto the interior of the opposite face ofthe housing to act against the removal of the idle stop unit. The teeth37 will mesh with the corresponding teeth formed in the housing toresist any rotation of the idle stop unit. Additional resistance torotation can be provided by placing a locking pin through aperture 38,which is located eccentrically on the idle stop unit.

1. A pedal mechanism comprising a pedal mounted on a first end of apivoted pedal arm, the second free end of the pedal arm being receivedwithin a housing, resistive means urging the pedal arm in one rotationaldirection and opposition means that engage with the second end of thepedal arm and oppose the urging of the resistive means, the oppositionmeans comprising one or more axial engagement means that engage with thehousing to resist axial movement of the opposition means and one or morerotational engagement means that engage with the housing to resistrotational movement of the opposition means.
 2. A pedal mechanismaccording to claim 1 in which the opposition means comprises aprojecting member that is parallel and eccentric with regard to the axisof the opposition means, the projecting member being received within thehousing.
 3. A pedal mechanism according to claim 1, in which therotational engagement means comprise one or more teeth that engage withcorresponding teeth formed in the housing.
 4. A pedal mechanismaccording to claim 1, in which the rotational engagement means comprisean elongate member inserted through an aperture within the oppositionmeans.
 5. A pedal mechanism according to claim 1, in which the axialengagement means comprise one or more resilient members that grip theinternal surface of the housing.
 6. An apparatus for opposing the motionof a foot pedal comprising a column, one or more axial engagement meansand one or more rotational engagement means, the column, in use,opposing the rotational motion of a foot pedal.
 7. An apparatusaccording to claim 6 in which the column comprises a projecting memberthat is parallel and eccentric with regard to the axis of the column,the projecting member being configured to engage, in use, with anaperture.
 8. An apparatus according to claim 6, in which the rotationalengagement means comprise one or more teeth configured to engage, inuse, with corresponding teeth.
 9. An apparatus according to claim 6, inwhich the rotational engagement means comprise an elongate memberconfigured to engage with an aperture within the apparatus.
 10. Anapparatus according to claim 6, in which the axial engagement meanscomprise one or more resilient members configured to engage, in use, asurface.
 11. A pedal mechanism according to claim 2, in which therotational engagement means comprise one or more teeth that engage withcorresponding teeth formed in the housing.
 12. An apparatus according toclaim 7, in which the rotational engagement means comprise one or moreteeth configured to engage, in use with corresponding teeth.
 13. Anapparatus according to claim 7, in which the rotational engagement meanscomprise an elongate member configured to engage with an aperture withinthe apparatus.
 14. An apparatus according to claim 8, in which therotational engagement means comprise an elongate member configured toengage with an aperture within the apparatus.
 15. An apparatus accordingto claim 12, in which the rotational engagement means comprise anelongate member configured to engage with an aperture within theapparatus.
 16. An apparatus according to claim 7, in which the axialengagement means comprise one or more resilient members configured toengage, in use, a surface.
 17. An apparatus according to claim 8, inwhich the axial engagement means comprise one or more resilient membersconfigured to engage, in use, a surface.
 18. An apparatus according toclaim 12, in which the axial engagement means comprise one or moreresilient members configured to engage, in use, a surface.
 19. Anapparatus according to claim 9, in which the axial engagement meanscomprise one or more resilient members configured to engage, in use, asurface.
 20. An apparatus according to claim 13, in which the axialengagement means comprise one or more resilient members configured toengage, in use, a surface.
 21. An apparatus according to claim 14, inwhich the axial engagement means comprise one or more resilient membersconfigured to engage, in use, a surface.
 22. An apparatus according toclaim 15, in which the axial engagement means comprise one or moreresilient members configured to engage, in use, a surface.